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Description of application of computer technology in flow meter

Since the application of computer technology in flow measurement instruments, the performance of flow meter has made a leap, borrowing computer-rich hardware and software resources, so that the flow measurement instrument has data processing capability and logic judgment ability, thereby improving accuracy and reliability; Its function is increased, and the operation is flexible and convenient. The following is a brief introduction to the common functional units of computer technology in flow meters. Most of these functional units have been placed in the transmitter, but some are also placed in display instruments or sensors such as calculators. .

Make the meter have calculus function
(l) achieve square root operation and small signal removal
In a differential pressure electromagnetic flowmeter, the flow rate is proportional to the square root of the differential pressure. Therefore, the differential pressure signal is subjected to an open square operation. The square root operation is realized by a single computer in the transmitter, and the accuracy is not substantially lost.
Small signal cut-off by the single-chip microcomputer in the transmitter can not only set the cut-off point arbitrarily, but also can set the cut-off dead zone [13] to avoid oscillation near the cut-off point. The cut point can be adjusted quite accurately.
(2) Correction of the influence of the second and third parameters [14]
For example, in a differential pressure transmitter, the ambient temperature and the process static pressure will affect the zero point and range of the meter. Therefore, when the instrument is manufactured, the influence amount is measured and tested, and with the help of the single-chip microcomputer, according to the ambient temperature sensor and The process static pressure sensor output automatically corrects the zero and span of the meter, which can improve the accuracy of the whole machine to the level of Ol or even higher.
(3) Realization of conversion of engineering units
For example, the IFM4100 electromagnetic flowmeter of Shanghai Guanghua·Aihe Meite Instrument Co., Ltd., the instantaneous flow unit can be 11i3ls, m3/min, m3/h, L/s, L/min, Uh, US G/s, US G/ The choice between min, US G/h, etc., and the flow coefficient value is automatically converted when the unit is changed.
(4) for various other calculations
A typical example is the calculation of mass flow in a multivariable transmitter (taking gas as an example) including [16]:
a. Calculate the throttle aperture d in the working state from the material expansion coefficient ^d, the fluid temperature f and the throttle opening diameter d20 at 20C:
b. Calculate the inner diameter D of the pipe under working condition by the material expansion coefficient ^d, o and the inner diameter D::o of the pipe at 20 °C;
c. From the medium viscosity p, mass flow rate q. And the mouth to calculate the Reynolds number threat D;
d. Calculate the diameter ratio p from d and D, and calculate the outflow coefficient c from Lu and ship D;
e. Calculating the swellability coefficient £1 from the isentropic index K and Ap, n Lu of the medium;
f. Calculate the fluid density Pl in the working state from the physical property parameters and t, p;
g. Calculate the mass flow rate q, h from c, p, e, d, Ap and household 1 according to the flow formula (15.35), thus achieving differential pressure
Full compensation for traffic.
h. For the calculation of the price, the payment is calculated by multiplying the cumulative rate by the different time periods specified in the agreement between the buyer and the seller and the different rates.

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